Credits will not add or will not be taken off on a Gottlieb.

Gottlieb credit unit will not step up or down

Cause: The credit (replay) unit is an up/down stepper with a known binding point in its mechanism.

Checks

• Work the unit by hand in both directions and look for where it catches.

Fix

• Clean the binding point and the unit's pivots, then retest.

Systems

• Electro-mechanical

Related tips

• Gottlieb player unit
• Game will not work: stepper unit binding
• Gottlieb Ax/Bx/Dx relays, coin unit and player unit: what each does
• Player unit sticks: clean off old lubricant, don't add more
• Stepper will not step reliably: sticky activator arms
• Players, credits or ball count not resetting points to a stepper unit
• Start button adds players 1 to 3 but never the 4th: adjust the coin unit end switch
• What stepper units do in an EM

Source: Repairing Electro-Mechanical (EM) Coin Operated Games to 1978, Part One, Clay Harrell (pinrepair.com)